1,720,956 research outputs found
Ferric Oxidation of Xylenol Orange as a Colorimetric Assay for Lipoxygenase Isoenzymes from Glycine Max
No full textThe focus of this study was to adapt the FOX method of Waslidge and Hayes (Anal. Biochem. 231, pp. 354-358, 1995) for assaying platelet lipoxygenase to make an assay for lipoxygenase isoenzymes from soybean (Glycine max.) The lipoxygenase enzyme is responsible for the formation of conjugated hydroperoxides from polyunsaturated fatty acids and molecular oxygen. Soybeans have multiple isoenzymes that catalyze this reaction. Three isoenzymes have been found in the seed while at least five different isoenzymes have been found in the vegetative tissue. Typical assays for lipoxygenase activity during enzyme purification have relied on monitoring the absorbance of the conjugated hydroperoxide at 230 nm. Such as assays have proven to be very time consuming. The FOX method allowed for batch assaying of multiple samples for lipoxygenase activity. The FOX method, or ferric oxidation of xylenol orange, took advantage of the fact that under low pH conditions, the hydroperoxides formed by the enzyme oxidize Fe2+ to Fe3+. The resulting ferric ions then oxidized xylenol orange to form a stable blue product that had an absorbance at 589 nm. The Waslidge and Hayes method was modified and optimized to assay soybean lipoxygenase isoenzymes using a spectrophotometer. This modified assay will expedite future enzyme isolation and purification studies
Going Beyond Counting First Authors in Author Co-citation Analysis
Get PDFThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Variations on the Author
Get PDF“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Appropriate Similarity Measures for Author Cocitation Analysis
Get PDFWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
Dispelling the Myths Behind First-author Citation Counts
Get PDFWe conducted a full-scale evaluative citation analysis study of scholars in the XML research field to explore just how different from each other author rankings resulting from different citation counting methods actually are, and to demonstrate the capability of emerging data and tools on the Web in supporting more realistic citation counting methods. Our results contest some common arguments for the continued
use of first-author citation counts in the evaluation of scholars, such as high correlations between author rankings by first-author citation counts and other citation
counting methods, and high costs of using more realistic citation counting methods that are not well-supported by the ISI databases. It is argued that increasingly available digital full text research papers make it possible for citation analysis studies to go beyond what the ISI databases have directly supported and to employ more
sophisticated methods
koamabayili/VECTRON-author-checklist: VECTRON author checklist
No full textWe have done our best to complete the author checklist relating to the use of animals in the hut study. Note that the objective for the hut study was to evaluate the IRS treatment applications for residual efficacy against Anopheles mosquitoes, including the local An. coluzzii mosquito population. Cows were only used to attract mosquitoes into the huts and no tests were carried out directly on the cows. The author checklist is intended for use with studies where experiments are carried out on animals, which is why we have had such difficulty in completing this for the hut study, as many of the questions do not relate to how the cows were used
Author-wise bibliometric analysis based on entropy.
No full textAuthor-wise bibliometric analysis based on entropy.</p
Recommended from our members
Advancing Analytical Methods for Characterization of Anionic Carbohydrate Biopolymers
Get PDFThe focus of this dissertation is on the development of improved analytical methods for the characterization of anionic carbohydrate biopolymers. Our goal is to extract important information from complex mixtures of heterogeneous polysaccharides by characterizing their substituent oligosaccharides in terms of monosaccharide composition and primary and secondary structure. This work focuses on the application of two major analytical platforms: spectroscopy and chromatography. The development of new nuclear magnetic resonance spectroscopy (NMR) tools for the characterization of the biologically active carbohydrates heparin and heparan sulfate (HS) is presented in Chapters 2-4. These biopolymers are members of a special class of nitrogen containing polysaccharides called glycosaminoglycans (GAGs). Our discovery of experimental parameters for detection of the 1H and 15N resonances of the sulfamate (NHSO3-) groups of the N-sulfoglucosamine residues of heparin and HS was an important breakthrough and demonstrated the sensitivity of these chemical shifts to local structure. Evaluation of the exchange kinetics of the sulfamate group protons with the bulk aqueous solvent allowed us to explore the relationship between primary and secondary structure in heparin oligosaccharides and led to our identification of the first solution state hydrogen bond between a sulfamate group NH proton and the adjacent 3-O-sulfate moiety of the heparin drug Arixtra (Fonduparinux sodium). Generation of a 1H and 15N chemical shift library for a series of heparin-derived oligosaccharides and chemically modified heparins allowed the assignment of the [1H,15N] HSQC correlations in spectra measured for unfractionated and low-molecular-weight heparins (LMWH) as well as commercial and human-derived 15N-enriched HS isolated from cell culture. The analysis of LMWH samples by reversed-phase ion-pairing ultraperformance liquid chromatography with detection by mass spectrometry (RPIP-UPLC-MS) is described in Chapter 5. This method utilizes volatile amphiphilic ion-pairing reagents to retain anionic oligosaccharides on a hydrophobic stationary phase while facilitating detection with the information rich method of mass spectrometry. With this platform we were able to separate individual components of complex LMWH mixtures providing a fingerprint of different drug preparations. The potential of this approach for quality assurance applications was illustrated by the comparison of the relative abundances of individual oligosaccharides highlighting slight differences between LMWH samples
- …
